Display panel

ABSTRACT

The display panel includes a first substrate, a second substrate, pixel structures, a liquid crystal layer and a transparent conductive layer. The liquid crystal layer is disposed between the pixel structures and the second substrate. The transparent conductive layer is disposed between the second substrate and the liquid crystal layer. When a liquid crystal molecule of the liquid crystal layer is a positive liquid crystal molecule, an absolute voltage difference between the transparent conductive layer and the common electrode is smaller than or equal to 2.3 volts(V). When the liquid crystal molecule of the liquid crystal layer is a negative liquid crystal molecule, the absolute voltage difference between the transparent conductive layer and the common electrode is smaller than or equal to 5V.

RELATED APPLICATIONS

This application claims priority to China Application Serial Number201610404033.1 filed Jun. 8, 2016, which is herein incorporated byreference.

BACKGROUND Field of Invention

The present invention relates to a display panel. More particularly, thepresent invention relates to a transverse-electric-field type displaypanel in which a transparent conductive layer is additionally disposedbetween two substrates.

Description of Related Art

In general, a shielding electrode layer is disposed on a surface of acolor filter substrate opposite to a liquid crystal layer in a displaypanel in order to prevent the vision effect of the display panel frombeing affected by the accumulation of electrostatic charges. Theshielding electrode layer has to be transparent, and therefore thematerial of the shielding electrode layer generally includes transparentconductive material such as Indium tin oxide (ITO). FIG. 1 is a diagramillustrating a cross-sectional view of a conventionaltransverse-electric-field type display panel. Referring to FIG. 1, adisplay panel 100 includes a shielding electrode layer 110, an uppersubstrate 120, a black matrix layer 130, an over-coating layer 140, aliquid crystal layer 150, a common electrode 161, an insulation layer162, a pixel electrode 163 and a lower substrate 170. A transverseelectric field is generated between the common electrode 161 and thepixel electrode 163 to change the orientation of a liquid crystalmolecule. The shielding electrode layer 110 can prevent the displayperformance of the panel from being affected by the electrostaticcharges or electromagnetic waves. However, in the conventional art, theshielding electrode layer is formed on the surface of the color filtersubstrate opposite to the liquid crystal layer while a thinner displaypanel gradually becomes the mainstream of the market, and therefore ingeneral, a thinning process is performed after the thin film transistorsubstrate is bonded to the color filter substrate, and then theshielding electrode layer is formed on the color filter substrate. Theconventional process is very complicated and the transportation cost isrelatively high. The recent trend is that the shielding electrode layeris formed on the surface of the color filter substrate facing the liquidcrystal layer before the process of bonding the thin film transistorsubstrate with the color filter substrate and the thinning process. Forthe transverse-electric-field type display panel, the operation ofmoving the shielding electrode layer into the inner side of the colorfilter substrate results in that the vertical electric field between theshielding electrode layer and the pixel electrode causes anunpredictable orientation of the liquid crystal molecule, and thus thedisplay performance is affected. Therefore, it is an issue for thepeople in the art about how to address the display-performance problemcaused by moving the shielding electrode layer into the inner side ofthe color filter substrate.

SUMMARY

An objective of the invention is to provide a display panel with bettertransmittance or contrast ratio.

Embodiments of the present invention provide a display panel including afirst substrate, a second substrate, pixel structures, a liquid crystallayer and a transparent conductive layer. The second substrate isdisposed opposite to the first substrate. The pixel structures aredisposed between the first substrate and the second substrate. Each ofthe pixel structures includes a thin film transistor, a pixel electrodeand a common electrode. The liquid crystal layer is disposed between thepixel structures and the second substrate. The transparent conductivelayer is disposed between the second substrate and the liquid crystallayer. When a liquid crystal molecule of the liquid crystal layer is apositive liquid crystal molecule, an absolute voltage difference betweenthe transparent conductive layer and the common electrode is smallerthan or equal to 2.3 volts(V). When the liquid crystal molecule of theliquid crystal layer is a negative liquid crystal molecule, the absolutevoltage difference between the transparent conductive layer and thecommon electrode is smaller than or equal to 5V.

In some embodiments, when the liquid crystal molecule of the liquidcrystal layer is the positive liquid crystal molecule, the absolutevoltage difference between the transparent conductive layer and thecommon electrode is smaller than or equal to 2.3V and is greater than orequal to 1V.

In some embodiments, when the liquid crystal molecule of the liquidcrystal layer is the positive liquid crystal molecule, the absolutevoltage difference between the transparent conductive layer and thecommon electrode is smaller than or equal to 2V and is greater than orequal to 1.4V.

In some embodiments, when the liquid crystal molecule of the liquidcrystal layer is the positive liquid crystal molecule, the absolutevoltage difference between the transparent conductive layer and thecommon electrode is equal to 1.7V.

In some embodiments, when the liquid crystal molecule of the liquidcrystal layer is the negative liquid crystal molecule, the absolutevoltage difference between the transparent conductive layer and thecommon electrode is smaller than or equal to 4V and is greater than orequal to 1V.

In some embodiments, when the liquid crystal molecule of the liquidcrystal layer is the negative liquid crystal molecule, the absolutevoltage difference between the transparent conductive layer and thecommon electrode is smaller than or equal to 3V and is greater than orequal to 2V.

In some embodiments, when the liquid crystal molecule of the liquidcrystal layer is the negative liquid crystal molecule, the absolutevoltage difference between the transparent conductive layer and thecommon electrode is equal to 2V.

In some embodiments, an insulation layer is disposed on the thin filmtransistor. The insulation layer is disposed on the pixel electrode, thecommon electrode is disposed on the insulation layer, and the commonelectrode has multiple slits.

In some embodiments, an insulation layer is disposed on the thin filmtransistor. The insulation layer is disposed on the common electrode,the pixel electrode is disposed on the insulation layer, and the pixelelectrode has multiple slits.

In some embodiments, an insulation layer is disposed on the thin filmtransistor. The pixel electrode and the common electrode are disposed onthe insulation layer coplanarly. Each of the common electrode and thepixel electrode respectively comprises multiple finger-type electrodes,and the finger-type electrodes of the common electrode are interlacedwith the finger-type electrodes of the pixel electrode.

In some embodiments, a black matrix layer is disposed between the secondsubstrate and the liquid crystal layer. The transparent conductive layeris disposed between the second substrate and the black matrix layer.

In some embodiments, a black matrix layer is disposed between the secondsubstrate and the liquid crystal layer. An over-coating layer isdisposed between the black matrix layer and the liquid crystal layer.The transparent conductive layer is disposed between the black matrixlayer and the over-coating layer.

In some embodiments, a black matrix layer is disposed between the secondsubstrate and the liquid crystal layer. An over-coating layer isdisposed between the black matrix layer and the liquid crystal layer.The transparent conductive layer is disposed between the over-coatinglayer and the liquid crystal layer.

In some embodiments, a voltage of the transparent conductive layer isequal to a voltage of the common electrode in a first frame period and asecond frame period next to the first frame period. The voltage of thecommon electrode in the first frame period is the same as that in thesecond frame.

In some embodiments, a voltage of the transparent conductive layer isgreater than a voltage of the common electrode in a first frame period.The voltage of the transparent conductive layer is smaller than thevoltage of the common electrode in a second frame period next to thefirst frame period, and the voltage of the common electrode in the firstframe period is the same as that in the second frame.

In some embodiments, the absolute voltage difference between thetransparent conductive layer and the common electrode in the first frameperiod is the same as that in the second frame period.

In some embodiments, the voltage of the common electrode has a directcurrent (DC) waveform, and the voltage of the transparent conductivelayer has an alternative current (AC) waveform.

In some embodiments, a voltage of the transparent conductive layer isgreater than or equal to a voltage of the common electrode in a firstframe period. The voltage of the transparent conductive layer is smallerthan or equal to the voltage of the common electrode in a second frameperiod next to the first frame period. The voltage of the commonelectrode in the first frame period is smaller than that in the secondframe.

In some embodiments, the absolute voltage difference between thetransparent conductive layer and the common electrode in the first frameperiod is the same as that in the second frame period.

In some embodiments, the voltage of the common electrode and the voltageof the transparent conductive layer have an alternative current (AC)waveform.

The invention, compared with the prior art, at least has advantages ofbetter contrast ratio or transmittance.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be more fully understood by reading the followingdetailed description of the embodiment, with reference made to theaccompanying drawings as follows.

FIG. 1 is a diagram illustrating a cross-sectional view of aconventional transverse-electric-field type display panel.

FIG. 2A is a diagram illustrating a top view of pixel structures in adisplay panel in accordance with an embodiment.

FIG. 2B-FIG. 2D are diagrams illustrating cross-sectional views oftransverse-electric-field type display panels in accordance with threedifferent embodiments.

FIG. 3A and FIG. 3B are diagrams illustrating curves of thetransmittance with respect to voltages in different embodiments.

FIG. 4A and FIG. 4B are diagrams illustrating curves of transmittancewith respect to different voltages in accordance with the embodiment ofFIG. 2B.

FIG. 5A and FIG. 5B are diagrams illustrating curves of transmittancewith respect to different voltages in accordance with the embodiment ofFIG. 2C.

FIG. 6A and FIG. 6B are diagrams illustrating curves of transmittancewith respect to different voltages in accordance with the embodiment ofFIG. 2D.

FIG. 7A illustrates a table for the brightness of display panel withrespect to the voltage difference between the transparent conductivelayer and the common electrode and the voltage difference between thepixel electrode and the common electrode in accordance with anembodiment.

FIG. 7B is a diagram illustrating a curve of contrast ratio with respectto the voltage difference between the transparent conductive layer andthe common electrode in accordance with the embodiment of FIG. 7A.

FIG. 7C illustrates a table for the brightness of display panel withrespect to the voltage difference between the transparent conductivelayer and the common electrode and the voltage difference between thepixel electrode and the common electrode in accordance with anotherembodiment.

FIG. 7D is a diagram illustrating a curve of contrast ratio with respectto the voltage difference between the transparent conductive layer andthe common electrode in accordance with the embodiment of FIG. 7C.

FIG. 8A and FIG. 8B are diagrams illustrating curves of transmittance ofthe display panel with different voltage differences between thetransparent conductive layer 230 and the common electrode 273 inaccordance with an embodiment.

FIG. 8C, FIG. 8D and FIG. 8E illustrates tables for transmittance of thedisplay panel with respect to the voltages difference between thetransparent conductive layer and the common electrode in accordance withan embodiment.

FIG. 9A and FIG. 9B are diagrams illustrating waveforms of the voltageson the pixel electrode 272, the common electrode 273 and the transparentconductive layer 230 in different frame periods in accordance with anembodiment.

FIG. 9C is a diagram illustrating waveforms of the voltages on the pixelelectrode 272, the common electrode 273 and the transparent conductivelayer 230 in different frame periods in accordance with an embodiment.

FIG. 10A is a diagram illustrating the top view of the display panel inaccordance with another embodiment.

FIG. 10B is a diagram illustrating a cross-sectional view of the displaypanel along a cut line II-II′ in FIG. 10A.

FIG. 10C and FIG. 10D are diagrams illustrating the cross-sectional viewof the display panel in accordance with different embodiments.

FIG. 10E is a diagram illustrating the top view of a pixel structure ina conventional IPS display panel.

FIG. 10F is a diagram illustrating a cross-sectional view of the displayalong with a cut line III-III′ in FIG. 10E.

DETAILED DESCRIPTION

Specific embodiments of the present invention are further described indetail below with reference to the accompanying drawings, however, theembodiments described are not intended to limit the present inventionand it is not intended for the description of operation to limit theorder of implementation. Moreover, any device with equivalent functionsthat are produced from a structure formed by a recombination of elementsshall fall within the scope of the present invention. Additionally, thedrawings are only illustrative and are not drawn to actual size.

The using of “first”, “second”, “third”, etc. in the specificationshould be understood for identifying units or data described by the sameterminology, but are not referred to particular order or sequence.

A transverse-electric-field type display panel such as an in-planeswitching (IPS) display panel, an IPS-Pro display panel, a fringe fieldswitching (FFS) display panel, or another display panel controllingliquid crystals by transverse electric field is provided. Thetransverse-electric-field type display panel includes a first substrateand a second substrate opposite to the each other. Multiple pixelstructures and a liquid crystal layer are disposed between the firstsubstrate and the second substrate. Note that the pixel structuresdescribed herein are the pixel structures disposed in the display regionof the display panel and do not include dummy pixel. Each pixelstructure includes a thin film transistor, a pixel electrode and acommon electrode. In particular, a transparent conductive layer isdisposed between the first substrate and the second substrate forshielding the display panel from static electricity or electromagneticwave. Several embodiments will be provided below to describe thedisposition and voltage of the transparent conductive layer (alsoreferred to as a shielding electrode layer).

Referring to FIG. 2A and FIG. 2B, FIG. 2A is a diagram illustrating atop view of pixel structures in a display panel in accordance with anembodiment, and FIG. 2B is a diagram illustrating a cross-sectional viewof the display panel viewed along a cut line I-I′ in FIG. 2A. A displaypanel 200 includes a first substrate 210 and a second substrate 220opposite to the each other. The first substrate 210 has a first surface210 a and a second surface 210 b opposite to the each other. The secondsubstrate 220 has a first surface 220 a and a second surface 220 bopposite to the each other. The first surface 210 a of the firstsubstrate 210 faces the first surface 220 a of the second substrate 220.A transparent conductive layer 230, a color filter layer 241, a blackmatrix layer 242, an over-coating layer 250, a liquid crystal layer 260and a pixel structure 270 are disposed between the first substrate 210and the second substrate 220. The pixel structure 270 is disposed on thefirst surface 210 a of the first substrate 210. The transparentconductive layer 230, the black matrix layer 242, the color filter layer241 and the over-coating layer 250 are sequentially disposed on thefirst surface 220 a of the second substrate 220. For simplification,only the pixel structure 270 on the first substrate 210 is illustratedin FIG. 2A, and not all units (e.g. may further including an alignmentfilm, a polarizer, etc.) are illustrated in FIG. 2B.

As shown in FIG. 2A and FIG. 2B, a gate line 281 and a data line 282 aredisposed on the first surface 210 a of the first substrate 210, and theyintersect to form a unit pixel region. Note that only one pixelstructure 270 formed in the unit pixel region is illustrated in FIG. 2Aand FIG. 2B, but in the embodiment, the display panel 200 includesmultiple pixel structures 270 formed respectively in different unitpixel regions. The pixel structure 270 includes a thin film transistor271, a pixel electrode 272 and a common electrode 273. The thin filmtransistor 271 has a drain electrode 271 a electrically connected to thepixel electrode 272, a source electrode 271 b electrically connected tothe data line 282, and a gate electrode 271 c electrically connected tothe gate line 281. A gate insulation layer 280 is formed between thegate electrode 271 c and a semiconductor layer 271 d. The commonelectrode 273 is disposed above the pixel electrode 272, and aninsulation layer 290 is disposed between the pixel electrode 272 and thecommon electrode 273. In other words, the insulation layer 290 isdisposed on the thin film transistor 271 and the pixel electrode 272,and the common electrode 273 is disposed on the insulation layer 290.The common electrode 273 has multiple slits 273 s. The pixel electrode272 is a plate structure without slits. When a voltage difference occursbetween the pixel electrode 272 and the common electrode 273, atransverse (horizontal) electric field is generated between the pixelelectrode 272 and the common electrode 273 to orient a liquid crystalmolecule 260L in the liquid crystal layer 260. People in the art shouldbe able to understand the operation principle of thetransverse-electric-field type display panel, and therefore the detailwill not be described herein.

The transparent conductive layer 230 is disposed on the first surface220 a of the second substrate 220 and has a first surface 230 a facingthe first substrate 210 and a second surface 230 b facing the secondsubstrate 220. The transparent conductive layer 230 is used forshielding the display panel 200 from the electromagnetic interference(EMI) so that the vision effect would not be affected. The transparentconductive layer 230 is also used to remove electrostatic charges on thesecond substrate 220 to avoid the accumulation of the electrostaticcharges on the display panel 200, which may result in the damage of thecomponents of the display panel 200 or an unexpected orientation of theliquid crystal molecule 260L affecting the display performance. Thematerial of the transparent conductive layer 230 may include indium tinoxide (ITO), indium zinc oxide (IZO), antimony tin oxide (ATO), fluorinetin oxide (FTO) or other conductive and transparent material.

The color filter layer 241 and the black matrix layer 242 are disposedon the first surface 230 a of the transparent conductive layer 230. Thecolor filter layer 241 includes multiple regions with respect todifferent colors (e.g. red, green and blue) to correspond to differentunit pixel regions. The black matrix layer 242 is disposed correspondingto the thin film transistor 271, the gate line 281, the data line 282 orother opaque regions, but the invention is not limited thereto. Theblack matrix layer 242 may be called light shielding layer. A materialof the black matrix layer 242 is, for example, black resin. However, theinvention is not limited thereto, and in other embodiments, the materialof the black matrix layer 242 can also be other light-shieldingmaterials.

The over-coating layer 250 is disposed between the color filter layer241/black matrix layer 242 and the liquid crystal layer 260. A surface241 a of the color filter layer 241 and a surface 242 a of the blackmatrix layer 242 facing the liquid crystal layer 260 have unevenstructures, and therefore the over-coating layer 250 has a planarsurface 250 a for planarization to avoid irregular inclined angles ofthe liquid crystal molecule 260L in the liquid crystal layer 260 causedby the uneven structures.

In the embodiment of FIG. 2B, the transparent conductive layer 230 isdisposed between the second substrate 220 and the color filter layer241/black matrix layer 242, but the invention is not limited thereto. Ifthe transparent conductive layer 230 is disposed between the secondsubstrate 220 and the liquid crystal layer 260, it provides thefunctions of shielding for EMI and discharging the electrostaticcharges. For example, in the embodiment of FIG. 2C, a display panel 300includes the transparent conductive layer 230 disposed between the colorfilter layer 241/black matrix layer 242 and the over-coating layer 250.In the embodiment of FIG. 2D, a display panel 400 includes thetransparent conductive layer 230 disposed between the over-coating layer250 and the liquid crystal layer 260. The difference between FIG. 2B,FIG. 2C and FIG. 2C is that the sequences of the color filter layer241/black matrix layer 242, the transparent conductive layer 230 and theover-coating layer 260 stacked on the second substrate 220 aredifferent. In the embodiments of FIG. 2C and FIG. 2D, the structure ofthe thin film transistor 271 and the connection between the thin filmtransistor 271 and the pixel electrode 272 are the same with that in theembodiment of FIG. 2B. Therefore, the thin film transistor 271 is notlabeled in FIG. 2C and FIG. 2D, and the structure of the thin filmtransistor 271, the connection between the thin film transistor 271 andthe pixel electrode 272 will not be repeated for simplification. Inaddition, the top view of the pixel structure in FIG. 2C and FIG. 2D maybe referred to FIG. 2A. The aforementioned different embodiments wouldaffect the transmittance (i.e. light transmittance, abbreviated totransmittance herein) of the display panels 200, 300 and 400differently. The type (e.g. positive or negative) of the liquid crystalmolecule 260L would also affect the orientation of the liquid crystalmolecule 260L relative to the electric field. Therefore, the influenceover the transmittance is discussed with respect to the positive liquidcrystal (LC) and negative LC.

FIG. 3A is a diagram illustrating curves of the transmittance withrespect to voltages in different embodiments. FIG. 3A illustrates curvesof transmittance of the display panel having positive LC, in which thehorizontal axis represents a pixel voltage and the vertical axisrepresents the transmittance of the display panel. There are four curves301-304 in FIG. 3A representing the conventional art in FIG. 1 and theembodiments of FIG. 2B to FIG. 2D respectively. The curves 301-304 havedifferent labels in accordance with the disposition sequence of thesecond substrate, the transparent conductive layer, the color filterlayer and the over-coating layer from top to down. To be specific, thecurve 301 corresponding to the FIG. 1 is labeled as “ITO/Glass/RGB/OC”;the curve 302 corresponding to FIG. 2B is labeled as “Glass/ITO/RGB/OC”;the curve 303 corresponding to FIG. 2C is labeled as “Glass/RGB/ITO/OC”;and the curve 304 corresponding to FIG. 2D is labeled as“Glass/RGB/OC/ITO”. As shown in FIG. 3A, the transmittance representedby the curve 302 is slightly lower than that of the curve 301, thetransmittance represented by the curve 303 is slightly lower than thatof the curve 302, and the transmittance represented by the curve 304significantly drops relative to the curves 301-303. In the conventionalart of FIG. 1, the transparent conductive layer is disposed on thesurface of the second substrate opposite to the liquid crystal layer,and therefore the distance between the transparent conductive layer andthe pixel electrode is equal to the summation of the thicknesses of thesecond substrate, the color filter layer, the over-coating layer, theliquid crystal layer and the insulation layer. However, the distancebetween the transparent conductive layer 230 and the pixel electrode 272is equal to the summation of the thicknesses of the color filter layer241, the over-coating layer 250, the liquid crystal layer 260 and theinsulation layer 290 in the embodiment of FIG. 2B, and is equal to thesummation of the thicknesses of the over-coating layer 250, the liquidcrystal layer 260, and insulation layer 290 in the embodiment of FIG.2C, and is equal to the summation of the thicknesses of the liquidcrystal layer 260 and the insulation layer 290 in the embodiment of FIG.2D. The vertical electric field between the transparent conductive layer230 and the pixel electrode 272 is proportional to the voltagedifference between the transparent conductive layer 230 and the pixelelectrode 272 divided by the distance between the transparent conductivelayer 230 and the pixel electrode 272, and therefore the verticalelectric fields between the transparent conductive layer 230 and thepixel electrode 272 in FIG. 1 and FIG. 2B to FIG. 2D have a relation ofFIG. 2D>FIG. 2C>FIG. 2B>FIG. 1. The liquid crystal molecule 260L isdriven by the transverse electric field between the pixel electrode 272and the common electrode 273 to control the transmittance of the displaypanels in the embodiments of FIG. 1, FIG. 2B-2D, and therefore when thevertical electric field between the transparent conductive layer 230 andthe pixel electrode 272 is too large, it would cause an unexpectedorientation of the liquid crystal molecule 260L and thus thetransmittance drops. FIG. 3B is a diagram illustrating curves of thedisplay panel having negative LC. Curve 311-314 correspond to theconventional art in FIG. 1, and the embodiments of FIG. 2B to FIG. 2Drespectively. Similarly, the transmittance represented by the curve 312is slightly lower than that by the curve 311, the transmittancerepresented by the curve 313 is slightly lower than that by the curve312, and the transmittance represented by the curve 314 significantlydrops relative to the curves 311-103. It is known from FIG. 3A and 3Bthat the transmittance just slightly drops compared with theconventional art no matter the transparent conductive layer 230 isdisposed between the second substrate 220 and the color filter layer 241or disposed between the color filter layer 241 and the over-coatinglayer 250, and no matter positive LC or negative LC is used. Note thatthe voltage between the transparent conductive layer 230 and the commonelectrode 273 is 0V in the embodiments of FIG. 3A and FIG. 3B.

Referring to FIG. 2B to FIG. 2D, how the voltage of the transparentconductive layer 230 is determined will be described below. Basically,the electric field between the common electrode 273 and the pixelelectrode 272 determines the orientation of the liquid crystal molecule260L. For example, when the common electrode 273 and the pixel electrode272 have the same voltage (i.e. the voltage difference between thecommon electrode 273 and the pixel electrode 272 is equal to 0), thelight will be blocked by the polarizer, and thus the display panel 200is in a dark state (i.e. color of black is shown). In contrast, when anabsolute voltage difference between the common electrode 273 and thepixel electrode 272 is maximized, the orientation of the liquid crystalmolecule 260L would maximize the light passing through the polarizer,and thus the display panel 200 is in a bright state. The brightness ofthe display panel 200 in the bright state divided by the brightness inthe dark state is referred to as contrast ratio (CR). Note that when avoltage difference occurs between the transparent conductive layer 230and the pixel electrode 272 or the common electrode 273, the verticalelectric field occurs between the transparent conductive layer 230 andthe pixel electrode 272 or the common electrode 273, and the electricfield may affect the orientation of the liquid crystal molecule 260L andaffect the transmittance and the contrast ratio. In the invention, thevoltage of the transparent conductive layer 230 is set to be in aparticular range so that the display panel 200 has better CR and/ortransmittance. Experimental data is provided below.

The transmittance is first discussed. Three embodiments show shown inthe following Table 1. In the first embodiment, the voltage of thecommon electrode 273 is 1 volts (V), and the voltage of the pixelelectrode 272 is in a range from 1V to 6V. In the second embodiment, thevoltage of the common electrode 273 is 0V, and the voltage of the pixelelectrode 272 is in a range from 0V to 5V. In the third embodiment, thevoltage of the common electrode 273 is −1V, and the voltage of the pixelelectrode 272 is in a range from −1V to 4V. The three embodiments haveone thing in common that the voltage difference between the commonelectrode 273 and the pixel electrode 272 is 0V in the dark state, andthe absolute voltage difference between the common electrode 273 and thepixel electrode 272 is 5V in the bright state. However, the absolutevoltage difference between the common electrode 273 and the pixelelectrode 272 in the bright state may be 4V, 6V or other values in otherembodiments.

TABLE 1 common electrode pixel electrode 1 V 1 V-6 V 0 V 0 V-5 V −1 V  −1 V-4 V  

If the voltage of the transparent conductive layer 230 has threepossibilities of −1V, 0V and 1V, and the three embodiments of Table 1are also considered, then the voltage difference between the transparentconductive layer 230 and the common electrode 273 would have 9embodiments as shown in the following Table 2.

TABLE 2 voltage of transparent conductive layer minus voltage of thepixel electrode maximum pixel common electrode (bright transparentconductive layer electrode state) −1 V 0 V 1 V −1 V   4 V −5 V −4 V −3 V0 V 5 V −6 V −5 V −4 V 1 V 6 V −7 V −6 V −5 V

For example, if the third embodiment of Table 1 is adopted and thevoltage of the transparent conductive layer is −1V, then the voltage ofthe transparent conductive layer 230 minus the voltage of the pixelelectrode 272 is −1−4=−5(V), and so on. In Table 2, the voltagedifference between the transparent conductive layer 230 and the pixelelectrode 272 has maximum of −3V and minimum of −7V. In general, whenthe absolute voltage difference between the transparent conductive layer230 and the pixel electrode 272 gets larger, the liquid crystal molecule260L between the transparent conductive layer 230 and the pixelelectrode 272 would be affected by the vertical electric field betweenthe transparent conductive layer 230 and the pixel electrode 272 moreseriously, and thus the transmittance drops. Therefore, the larger theabsolute voltage difference between the transparent conductive layer 230and the pixel electrode 272 is, the lower the transmittance of thedisplay panel is. That is to say, the smaller the absolute voltagedifference is, the higher the transmittance is. In Table 2, the besttransmittance occurs when the voltage of the transparent conductivelayer 230 is 1V and the voltage of the common electrode 273 is −1V ; andthe worst transmittance occurs when the voltage of the transparentconductive layer 230 is −1V and the voltage of the common electrode 273is 1V. Experimental data will be provided to support the statement.

FIG. 4A and FIG. 4B are diagrams illustrating curves of transmittancewith respect to different voltages in accordance with the embodiment ofFIG. 2B. Referring to FIG. 4A and FIG. 4B, the horizontal axisrepresents the voltage difference between the pixel electrode 272 andthe common electrode 273, the vertical axis represents the transmittanceof the display panel. FIG. 4A illustrates the transmittance of thedisplay panel having positive LC, in which the curve labeled as“Reference(Positive LC)” corresponds to the conventional art of

FIG. 1. FIG. 4B illustrates the transmittance of the display panelhaving negative LC, in which the curve labeled as “Reference(NegativeLC)” corresponds to the conventional art of FIG. 1. Regarding the othercurves, “CF” represent the transparent conductive layer 230 on thesecond substrate 220, and “Array” represents the common electrode 273 onthe first substrate 210. For example, the curve labeled as“CF_1V/Array_−1V ” represents the transmittance when the voltage of thetransparent conductive layer 230 is 1V and the voltage of the commonelectrode 273 is −1V, and so on. In FIG. 4A, the curve 401 labeled as“CF_1 V/Array_−1V ” has the highest transmittance, the curve 402 labeledas “CF_−1V/Array_−1V” has the lowest transmittance. In FIG. 4B, thecurve 411 labeled as “CF_1V/Array_−1V ” has the highest transmittance,and the curve 412 labeled as “CF_−1V/Array_1V ” has the lowesttransmittance.

Note that as discussed, there are 9 embodiments with respect to thevoltages between the transparent conductive layer 230 and the commonelectrode 273, but not all 9 embodiments are illustrated in FIG. 4A andFIG. 4B for clearly illustrating the curves. Complete data of the 9embodiments in FIG. 4A is shown in the following Table 3. To bespecific, four curves of “CF_−1V/Array_0V ”, “CF_0V/Array_0V ”,“CF_0V/Array_−1V ”, and “CF_−1V/Array_−1V ” are omitted in FIG. 4A, butthe transmittances represented by the four curves are not higher thancurve 401 and not lower than the curve 402. In the following Table 3,the first column represents the voltage difference (i.e. the horizontalaxis in FIG. 4A) between the pixel electrode 272 and the commonelectrode 273, the percentages shown in the table represent thetransmittances (i.e. the vertical axis in FIG. 4A), and “CR” representsthe contrast ratio. Note that “Substrate_Shielding_BM/RGB_OC” in Table 3corresponds to the structures of FIG. 2B, and that is, the secondsubstrate 220, the transparent conductive layer 230, the black matrixlayer 242/color filter layer 241,and the over-coating layer 250 aredisposed from top to down. In other words, the transparent conductivelayer 230, the black matrix layer 242/color filter layer 241,and theover-coating layer 250 are sequentially stacked on the second substrate220.

TABLE 3 Substrate_shielding_BM/RGB_OC Positive LC CF_−1 V/ CF_1 V/Array_−1 V CF_0 V/Array_−1 V Array_−1 V 0 0.01% 0.01% 0.01% 0.5 0.01%0.01% 0.01% 1 0.04% 0.04% 0.06% 1.5 0.22% 0.22% 0.30% 2 1.15% 1.36%1.67% 2.5 4.10% 4.30% 4.73% 3 7.27% 7.58% 8.03% 3.5 9.89% 10.34% 10.72%4 11.72% 12.23% 12.62% 4.5 12.84% 13.41% 13.77% 5 13.40% 14.02% 14.36%CR 1341.012193 1402.389166 1431.806766 CF_−1 V/Array_0 V CF_0 V/Array_0V CF_1 V/Array_0 V 0 0.01% 0.01% 0.01% 0.5 0.01% 0.01% 0.01% 1 0.03%0.04% 0.04% 1.5 0.24% 0.21% 0.24% 2 1.37% 1.22% 1.27% 2.5 3.91% 3.86%4.30% 3 6.69% 7.25% 7.58% 3.5 9.06% 9.89% 10.31% 4 10.78% 11.73% 12.23%4.5 11.88% 12.85% 13.41% 5 12.43% 13.40% 14.01% CR 1243.2692611340.573503 1401.168337 CF_−1 V/Array_1 V CF_0 V/Array_1 V CF_1V/Array_1 V 0 0.01% 0.01% 0.01% 0.5 0.01% 0.01% 0.01% 1 0.04% 0.03%0.03% 1.5 0.31% 0.24% 0.21% 2 1.14% 1.37% 1.23% 2.5 2.57% 3.89% 4.06% 34.54% 6.68% 7.30% 3.5 6.70% 9.06% 9.88% 4 8.50% 10.78% 11.72% 4.5 9.79%11.88% 12.84% 5 10.46% 12.44% 13.40% CR 1042.893569 1244.3252841340.515467

On the other hand, complete data of the 9 embodiments in FIG. 4B isshown in the following Table 4. Three curves of “CF_−1V/Array_0V ”,“CF_−1V/Array_−1V ” and “CF_0V/Array_−1V ” are omitted in FIG. 4B.Similarly, the transmittances represented by the omitted three curvesare not higher than the curve 411, and not lower than the curve 412. Thedrawing principle for Table 4 is similar to that of Table. 3, andtherefore will not be repeated.

TABLE 4 Substrate_Shielding_BM/RGB_OC Negative LC CF_−1 V/ CF_0 V/ CF_1V/ Array_−1 V Array_−1 V Array_−1 V 0 0.01% 0.01% 0.01% 0.5 0.01% 0.01%0.01% 1 0.02% 0.03% 0.03% 1.5 0.11% 0.13% 0.13% 2 0.49% 0.60% 0.72% 2.52.16% 2.48% 2.31% 3 4.91% 6.01% 6.27% 3.5 8.58% 9.21% 9.57% 4 11.18%11.71% 12.17% 4.5 13.05% 13.63% 13.76% 5 14.31% 14.77% 14.78% CR1427.833108 1474.010496 1474.261726 CF_−1 V/ CF_0 V/ CF_1 V/ Array_0 VArray_0 V Array_0 V 0 0.01% 0.01% 0.01% 0.5 0.01% 0.01% 0.01% 1 0.02%0.03% 0.03% 1.5 0.08% 0.11% 0.13% 2 0.40% 0.56% 0.54% 2.5 1.69% 2.00%2.24% 3 4.19% 5.31% 5.86% 3.5 7.71% 8.57% 9.20% 4 10.47% 11.30% 11.73%4.5 12.46% 13.16% 13.54% 5 13.90% 14.35% 14.63% CR 1386.6276661431.761898 1459.608408 CF_−1 V/ CF_0 V/ CF_1 V/ Array_1 V Array_1 VArray_1 V 0 0.01% 0.01% 0.01% 0.5 0.01% 0.01% 0.01% 1 0.02% 0.02% 0.02%1.5 0.07% 0.09% 0.11% 2 0.29% 0.35% 0.48% 2.5 1.23% 1.68% 1.83% 3 3.57%4.07% 5.02% 3.5 6.64% 7.68% 8.53% 4 9.35% 10.35% 11.12% 4.5 11.49%12.45% 13.08% 5 13.14% 13.89% 14.41% CR 1309.935512 1385.6985561437.979453

FIG. 5A and FIG. 5B are diagrams illustrating curves of transmittancewith respect to different voltages in accordance with the embodiment ofFIG. 2C. FIG. 5A illustrate the transmittance of the display panelhaving positive LC, and FIG. 5B illustrates the transmittance of thedisplay panel having negative LC. In FIG. 5A, the curve 501 labeled as“CF_1V/Array_−1V ” has the highest transmittance, and the curve 502labeled as “CF_−1V/Array_1V ” has the lowest transmittance. In FIG. 5B,the curve 511 labeled as “CF_1V/Array_−1V ” has the highesttransmittance, the curve 512 labeled as “CF_−1V/Array_1V ” has thelowest transmittance.

Similarly, not all 9 embodiments are illustrated in FIG. 5A, andcomplete data of the 9 embodiments is shown in the following Table 5. Tobe specific, four curves of “CF_−1V/Array_0V ”, “CF_0V/Array_−1V ”,“CF_0V/Array_0V ” and “CF_−1V/Array_−1V ” are omitted in FIG. 5A, butthe transmittances represented by the four omitted curves are not higherthan the curve 501 and not lower than the curve 502. Similarly,“Substrate_BM/RGB_Shielding_OC” in Table 5 corresponds to the structureof FIG. 2C, that is, the second substrate 220, the black matrix layer242/color filter layer 241, the transparent conductive layer 230, andthe over-coating layer 250 are disposed from top to down.

TABLE 5 Substrate_BM/RGB_Shielding_OC Positive LC CF_−1 V/ CF_0 V/ CF_1V/ Array_−1 V Array_−1 V Array_−1 V 0 0.01% 0.01% 0.01% 0.5 0.01% 0.01%0.02% 1 0.03% 0.04% 0.08% 1.5 0.18% 0.25% 0.46% 2 1.02% 1.19% 1.81% 2.54.03% 4.26% 5.07% 3 7.02% 7.60% 8.47% 3.5 9.45% 10.23% 10.87% 4 11.13%12.13% 12.73% 4.5 12.13% 13.31% 13.83% 5 12.64% 13.87% 14.40% CR1264.232586 1387.109964 1390.092671 CF_−1 V/ CF_0 V/ CF_1 V/ Array_0 VArray_0 V Array_0 V 0 0.01% 0.01% 0.01% 0.5 0.01% 0.01% 0.01% 1 0.04%0.03% 0.04% 1.5 0.29% 0.18% 0.22% 2 1.19% 0.91% 1.45% 2.5 2.64% 4.01%4.29% 3 4.40% 7.01% 7.55% 3.5 6.23% 9.45% 10.24% 4 7.98% 11.12% 12.13%4.5 9.14% 12.13% 13.33% 5 9.76% 12.64% 13.85% CR 976.1700288 1264.2815481384.638076 CF_−1 V/ CF_0 V/ CF_1 V/ Array_1 V Array_1 V Array_1 V 00.01% 0.01% 0.01% 0.5 0.02% 0.01% 0.01% 1 0.13% 0.04% 0.03% 1.5 0.60%0.28% 0.18% 2 1.60% 1.19% 0.93% 2.5 3.01% 2.64% 3.51% 3 4.58% 4.41%6.97% 3.5 6.00% 6.35% 9.43% 4 7.01% 8.00% 11.12% 4.5 7.57% 9.16% 12.13%5 7.80% 9.78% 12.63% CR 752.5104514 977.6306232 1263.689167

On the other hand, complete data of FIG. 5B is shown in the followingTable 6. Three curves of “CF_−1V/Array_0V ”, “CF_0V/Array_−1V ”, and “CF_0V/Array_0V ” are omitted in FIG. 5B, and the transmittancesrepresented by the three omitted curves are not higher than the curve511 and not lower than the curve 512.

TABLE 6 Substrate_BM/RGB_Shielding_OC Negative LC CF_−1 V/ CF_0 V/ CF_1V/ Array_−1 V Array_−1 V Array_−1 VC 0 0.01% 0.01% 0.01% 0.5 0.01% 0.01%0.01% 1 0.02% 0.03% 0.03% 1.5 0.10% 0.14% 0.16% 2 0.46% 0.60% 0.68% 2.51.84% 2.31% 2.37% 3 4.76% 5.93% 5.90% 3.5 7.90% 9.06% 9.58% 4 10.53%11.59% 12.05% 4.5 12.43% 13.30% 13.69% 5 13.87% 14.52% 14.81% CR1383.538816 1447.943582 1473.68574 CF_−1 V/ CF_0 V/ CF_1 V/ Array_0 VArray_0 V Array_0 V 0 0.01% 0.01% 0.01% 0.5 0.01% 0.01% 0.01% 1 0.02%0.02% 0.03% 1.5 0.07% 0.10% 0.13% 2 0.30% 0.47% 0.65% 2.5 1.19% 1.64%1.97% 3 3.30% 4.90% 5.47% 3.5 6.23% 7.87% 9.03% 4 8.95% 10.47% 11.60%4.5 11.03% 12.50% 13.34% 5 12.79% 13.84% 14.47% CR 1276.1102831380.490266 1443.912643 CF_−1 V/ CF_0 V/ CF_1 V/ Array_1 V Array_1 VArray_1 V 0 0.01% 0.01% 0.01% 0.5 0.01% 0.01% 0.01% 1 0.02% 0.02% 0.02%1.5 0.05% 0.07% 0.10% 2 0.17% 0.27% 0.43% 2.5 0.64% 1.11% 1.89% 3 2.10%3.21% 4.54% 3.5 4.55% 6.24% 7.87% 4 7.22% 8.92% 10.63% 4.5 9.35% 11.15%12.47% 5 11.21% 12.67% 13.85% CR 1115.696557 1263.904208 1381.81641

FIG. 6A and FIG. 6B are diagrams illustrating curves of transmittancewith respect to different voltages in accordance with the embodiment ofFIG. 2D. FIG. 6A illustrates the transmittance of the display panelhaving positive LC, and FIG. 6B illustrates the transmittance of thedisplay panel having negative LC. In FIG. 6A, except for the referencecurve 602, the curve 601 labeled as “CF_1 V/Array_−1V ” has the highesttransmittance, the curve 603 labeled as “CF_−1V/Array_1V ” has thelowest transmittance. In FIG. 6B, except for the reference curve 612,the curve 611 labeled as “CF_1V/Array_−1V ” has the highesttransmittance, and the curve 613 labeled as “CF_−1V/Array_1V ” has thelowest transmittance.

Complete data of FIG. 6A is shown in the following Table 7. Four curesof “CF_−1V/Array_0V ”, “CF_0V/Array_−1V ”, “CF_0V/Array_0V ”, and“CF−1V/Array_−1V ” are omitted in FIG. 6A, but the transmittancesrepresented by the four omitted curves are not higher than the curve 601and not lower than the curve 603. Similarly,“Substrate_BM/RGB_OC_Shielding” in Table 7 corresponds to the structureof FIG. 2D, that is, the second substrate 220, the black matrix layer242/color filter layer 241, the over-coating layer 250, and thetransparent conductive layer 230 are disposed from top to down.

TABLE 7 Substrate_BM/RGB_OC_Shielding Positive LC CF_−1 V/ CF_0 V/ CF_1V/ Array_−1 V Array_−1 V Array_−1 V 0 0.01% 0.01% 0.09% 0.5 0.01% 0.01%0.28% 1 0.03% 0.05% 0.50% 1.5 0.20% 0.26% 0.81% 2 1.21% 1.20% 1.42% 2.52.86% 3.88% 4.10% 3 3.98% 7.24% 7.21% 3.5 4.95% 9.80% 9.76% 4 5.85%11.50% 11.59% 4.5 6.54% 12.38% 13.05% 5 6.94% 12.71% 13.92% CR694.7747569 1262.236793 160.730722 CF_−1 V/ CF_0 V/ CF_1 V/ Array_0 VArray_0 V Array_0 V 0 0.01% 0.01% 0.01% 0.5 0.01% 0.01% 0.01% 1 0.10%0.03% 0.05% 1.5 0.50% 0.20% 0.25% 2 1.29% 1.22% 1.29% 2.5 2.25% 2.88%4.12% 3 3.12% 4.02% 7.24% 3.5 3.78% 4.95% 9.80% 4 4.21% 5.85% 11.50% 4.54.45% 6.54% 12.39% 5 4.56% 6.94% 12.71% CR 453.142883 694.64117941263.555208 CF_−1 V/ CF_0 V/ CF_1 V/ Array_1 V Array_1 V Array_1 V 00.09% 0.01% 0.01% 0.5 0.05% 0.01% 0.01% 1 0.29% 0.10% 0.03% 1.5 0.72%0.50% 0.17% 2 1.20% 1.29% 1.21% 2.5 1.64% 2.25% 2.86% 3 1.98% 3.12%4.08% 3.5 2.22% 3.78% 4.98% 4 2.43% 4.22% 5.87% 4.5 2.49% 4.45% 6.55% 52.54% 4.55% 6.96% CR 29.27983662 452.1263789 696.6168194

Complete data of FIG. 6B is shown in the following Table 8. Two curvesof “CF_0V/Array_0V ” and “CF_−1V/Array_−1V ” are omitted in the FIG. 6B,but the transmittances represented by the two omitted curves are nothigher than the curve 611 and not lower than the curve 613.

TABLE 8 Substrate_BM/RGB_OC_Shielding Negative LC CF_−1 V/ CF_0 V/ CF_1V/ Array_−1 V Array_−1 V Array_−1 V 0 0.01% 0.01% 0.01% 0.5 0.01% 0.01%0.01% 1 0.02% 0.03% 0.03% 1.5 0.06% 0.11% 0.12% 2 0.24% 0.40% 0.47% 2.50.87% 1.60% 1.74% 3 2.17% 4.60% 5.01% 3.5 5.07% 7.63% 8.49% 4 7.30%9.96% 10.93% 4.5 9.19% 11.79% 12.72% 5 10.75% 13.12% 13.93% CR1072.607216 1306.014322 1352.012857 CF_−1 V/ CF_0 V/ CF_1 V/ Array_0 VArray_0 V Array_0 V 0 0.01% 0.01% 0.01% 0.5 0.01% 0.01% 0.01% 1 0.01%0.02% 0.03% 1.5 0.03% 0.06% 0.10% 2 0.10% 0.24% 0.45% 2.5 0.29% 0.89%1.50% 3 0.81% 2.29% 3.98% 3.5 2.13% 4.89% 7.61% 4 4.03% 7.29% 9.98% 4.56.07% 9.18% 11.79% 5 7.65% 10.74% 13.15% CR 760.9103357 1071.9947461308.602663 CF_−1 V/ CF_0 V/ CF_1 V/ Array_1 V Array_1 V Array_1 V 00.01% 0.01% 0.01% 0.5 0.01% 0.01% 0.01% 1 0.01% 0.01% 0.02% 1.5 0.02%0.03% 0.06% 2 0.04% 0.09% 0.23% 2.5 0.11% 0.30% 0.87% 3 0.28% 0.82%2.62% 3.5 0.71% 2.14% 5.00% 4 1.75% 4.24% 7.29% 4.5 3.24% 6.04% 9.18% 55.01% 7.65% 10.74% CR 486.447791 761.4666732 1071.654355

Therefore, the best transmittance occurs when the voltage of thetransparent conductive layer 230 is 1V and the voltage of the commonelectrode 273 is −1V (that is, the difference between the voltage of thetransparent conductive layer 230 and the maximum voltage of the pixelelectrode 272 is −3V); the worst transmittance occurs when the voltageof the transparent conductive layer 230 is −1V and the voltage of thecommon electrode 273 is 1V (that is, the difference between the voltageof the transparent conductive layer 230 and the maximum voltage of thepixel electrode 272 is −7V) among the 9 embodiments according to thedata shown in FIG. 4A, FIG. 4B, FIG. 5A, FIG. 5B, FIG. 6A, FIG. 6B, andTable 3 to Table 8.

The contrast ratio is discussed herein. Data for the contrast ratio isshown as figures because the tables are too big. Brightness of thedisplay panel is listed in tables of FIG. 7A and FIG. 7C in accordancewith the voltage of the transparent conductive layer 230, the pixelelectrode 272 and the common electrode 273. The contrast ratiocorresponding to FIG. 7A and FIG. 7C are shown in FIG. 7B and FIG. 7Drespectively. FIGS. 7A and 7B are for positive LC, and FIG. 7C and FIG.7D are for negative LC.

Values in the first row of the tables in FIG. 7A and FIG. 7C representsthe voltage of the transparent conductive layer 230 minus the voltage ofthe common electrode 273, and the range is from 0V to 5V ; values in thefirst column represents the voltage of the pixel electrode 272 minus thevoltage of the common electrode 273, and the range is from 0V to 5V ;other values except for the last row are the brightness of the displaypanel. When the voltage difference between the pixel electrode 272 andthe common electrode 273 is 0V, the display panel is in the dark state,and therefore the brightness of the display panel is relatively low. Forexample, the brightness in the second row of FIG. 7A is in a range from0.5 to 13.1. When the voltage difference between the pixel electrode 272and the common electrode 273 is 5V, the display panel is in the brightstate, and therefore the brightness of the display panel is relativelyhigh. For example, the brightness in the second last row of FIG. 7A isin a range from 402 to 722. The contrast ratio, as shown in the last rowof FIG. 7A, is calculated by dividing the brightness of the bright stateby the brightness of the dark state.

Take the display panel with positive LC as an example, referring to FIG.7A and FIG. 7B, the vertical axis represent contrast ratio and thehorizontal axis represents the voltage difference between thetransparent conductive layer 230 and the common electrode 273 in FIG.7B. When the voltage difference between the transparent conductive layer230 and the common electrode 273 is 0V (refer to the second column ofFIG. 7A), the lowest brightness is 0.499779 (the number is rounded as0.5 in FIG. 7A), the highest brightness is 631.86 (the number is roundedas 632 in FIG. 7A), and therefore the contrast ratio is 1264. When thevoltage difference between the transparent conductive layer 230 and thecommon electrode 273 is 5V (refer to the last column), the lowestbrightness is 13.141548 (the number is rounded as 13.1 in FIG. 7A), thehighest brightness is 401.6571 (the number is rounded as 402 in FIG.7A), and therefore the contrast ratio is 31.

As shown in FIG. 7A and FIG. 7B, when the voltage difference between thetransparent conductive layer 230 and the common electrode 273 is greaterthan 2.3V, the contrast ratio of the display panel with positive LCdrops significantly. Therefore, in some embodiment, it is set that thevoltage of the transparent conductive layer 230 minus the voltage of thecommon electrode 273 is greater than or equal to 0V and smaller than orequal to 2.3V (i.e. 0V ≦the voltage of the transparent conductive layer230 minus the voltage of the common electrode 273≦2.3V). In addition,when the voltage difference between the transparent conductive layer 230and the common electrode 273 is smaller than 1V, the contrast ratio ofthe display panel slightly drops. Therefore, in some embodiments, it ispreferably set that the voltage of the transparent conductive layer 230minus the voltage of the common electrode 273 is smaller than or equalto 2.3V and greater than or equal to 1V. In some embodiments, it isfurther set that the voltage of the transparent conductive layer 230minus the voltage of the common electrode 273 is smaller than or equalto 2V and greater than or equal to 1.4V for further setting a preferredrange of contrast ratio. In some embodiments, it is set that the voltageof the transparent conductive layer 230 minus the voltage of the commonelectrode 273 is equal to 1.7V for maximizing the contrast ratio.

Note that when the display panel operates, the polarity of the liquidcrystal has to be reversed in adjacent frames to avoid the DC residualeffect. In the aforementioned embodiment, the voltage of the pixelelectrode 272 is greater than or equal to the voltage of the commonelectrode 273, and the voltage of the transparent conductive layer 230is greater than the voltage of the common electrode 273. After thepolarity is reversed (in the next frame), the voltage of the pixelelectrode 272 is smaller than the voltage of the common electrode 273,and therefore it may be set that the voltage of the transparentconductive layer 230 is smaller than the voltage of the common electrode273, and the voltage of the common electrode 273 minus the voltage ofthe transparent conductive layer 230 is smaller than or equal to 2.3Vfor obtaining a preferred contrast ratio. In other words, the absolutevoltage difference between the transparent conductive layer 230 and thecommon electrode 273 may be set as any voltage value which is greaterthan or equal to 0V and smaller than or equal to 2.3V, or as any voltagevalue which is smaller than or equal to 2.3V and greater than or equalto 1V, or as any voltage value which is smaller than or equal to 2V andgreater than or equal to 1.4V, or as 1.7V for obtaining a preferredcontrast ratio. Note that although the voltage of the common electrode273 is 0V in the embodiments of FIG. 7A and FIG. 7B, when the voltage ofthe common electrode 273 is altered, the voltage of the transparentconductive layer 230 may be altered correspondingly. For example, if thevoltage of the common electrode 273 is 1V, then the voltage of thetransparent conductive layer 230 may be set to be smaller than or equalto 3.3V and greater than or equal to −1.3V; if the voltage of the commonelectrode 273 is −1V, then the voltage of the transparent conductivelayer 230 may be set to be smaller than or equal to 1.3V and greaterthan or equal to −3.3V, and so on.

Referring to FIG. 7C and FIG. 7D, for the display panel having negativeLC, when the voltage difference between the transparent conductive layer230 and the common electrode 273 is in a range from 0V to 5V, thecontrast ratio of the display panel is higher than 1350. Therefore, insome embodiments, the absolute voltage difference between thetransparent conductive layer 230 and the common electrode 273 is set asany voltage value which is smaller than or equal to 5V and greater thanor equal to 0V. In addition, when the voltage difference between thetransparent conductive layer 230 and the common electrode 273 is greaterthan 4V or smaller than 1V, the contrast ratio of the display paneldrops significantly. Therefore, in some embodiments, the absolutevoltage difference between the transparent conductive layer 230 and thecommon electrode 273 is set as any voltage value which is smaller thanor equal to 4V and greater than or equal to 1V. Moreover, when thevoltage difference between the transparent conductive layer 230 and thecommon electrode 273 is greater than 3V or smaller than 2V, the contrastratio of the display panel drops slightly. Therefore, in someembodiments, the absolute voltage difference between the transparentconductive layer 230 and the common electrode 273 is set as any voltagevalue which is smaller than or equal to 3V and greater than or equal to2V. In some embodiments, the absolute voltage difference between thetransparent conductive layer 230 and the common electrode 273 ispreferably set as any voltage value which is smaller than or equal to2.9V and greater than or equal to 2V to set a preferred range of thecontrast ratio. In some embodiments, the absolute voltage differencebetween the transparent conductive layer 230 and the common electrode273 is set as 2V to maximize the contrast ratio.

FIG. 8A and FIG. 8B are diagrams illustrating curves of transmittance ofthe display panel with different voltage differences between thetransparent conductive layer 230 and the common electrode 273 inaccordance with an embodiment. Curves of transmittance for the displaypanel having positive LC are illustrated in FIG. 8A, and curves oftransmittance for the display panel having negative LC are illustratedin FIG. 8B. The horizontal axis represents the voltage differencebetween the pixel electrode 272 and the common electrode 273, and thevertical axis represents the transmittance. The label for each curverepresents the voltage difference between the transparent conductivelayer 230 and the common electrode 273. For clarity, not all data isshown in FIG. 8A and FIG. 8B. Complete data of FIG. 8A is shown in FIG.8C and FIG. 8D, in which the first row represent the voltage differencebetween the transparent conductive layer 230 and the common electrode273, and the first columns presents the voltage difference between thepixel electrode 272 and the common electrode 273, and other valuesrepresent the transmittances. In addition, complete data of FIG. 8B isshown in FIG. 8E. The drawing principle of FIG. 8E is similar to that ofFIG. 8C and FIG. 8D. In FIG. 8A, the curve 801 and the curve 802respectively represent the transmittances corresponding to the voltagedifferences 2.4V and 1.7V between the transparent conductive layer 230and the common electrode 273. The curve 801 is close to the curve 802,but the contrast ratio drops when the voltage difference between thetransparent conductive layer 230 and the common electrode 273 is 2.4V asshown in FIG. 7A and FIG. 7B, and therefore the display performance ofthe display panel in which the absolute voltage difference between thetransparent conductive layer 230 and the common electrode 273 is 1.7V isbetter than that of the display panel in which the absolute voltagedifference between the transparent conductive layer 230 and the commonelectrode 273 is 2.4V when both the transmittance and the contrast ratioare considered. Curves of transmittance for the voltage differences 0V,1V, 2V, 3V, 4V and 5V between the transparent conductive layer 230 andthe common electrode 273 are shown in FIG. 8B. The curve 811 representsthe voltage of 2V. As shown in FIGS. 8B and 8E, all curves oftransmittance are close to each other even the voltage differencesbetween the transparent conductive layer 230 and the common electrode273 are different from each other. The voltage difference between thetransparent conductive layer 230 and the common electrode 273 may be setmore flexibly to obtain better display performance for the display panelhaving negative LC, compared to the display panel having positive LC,because all contrast ratios in FIGS. 7C and 7D are very high even thevoltage differences between the transparent conductive layer 230 and thecommon electrode 273 are different.

The display performance of the display panel is determined based on thecontrast ratio and the transmittance. In addition, a circuit providingthe voltage to the transparent conductive layer 230 is designed inaccordance with the absolute voltage difference between the transparentconductive layer 230 and the common electrode 273. Accordingly, theabsolute voltage difference between the transparent conductive layer 230and the common electrode 273 can be set to be in an appropriate rangebased on the disclosure of FIG. 7A to FIG. 7D and FIG. 8C to FIG. 8E.For example, the absolute voltage difference between the transparentconductive layer 230 and the common electrode 273 may be set to begreater than or equal to x and smaller than or equal to y, where x and yare real numbers, and x is smaller than or equal to y. As discussedabove, for the display panel having positive LC, the contrast ratio ofthe display panel drops significantly when the absolute voltagedifference between the transparent conductive layer 230 and the commonelectrode 273 is greater than 2.3V, and the contrast ratio is higherthan 1200 when the voltage difference between the transparent conductivelayer 230 and the common electrode 273 is in a range from 0V to 2.3V.Therefore, the real number x may be 0, 1, 1.4, 1.7, or any real numberin a range from 0 to 1.7 (e.g. 0, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6 or 1.7as shown in FIG. 7A), and the real number y may be 1.7, 2.3, or any realnumber in a range from 1.7 to 2.3 (e.g. 1.7, 1.8, 1.9, 2, 2.1, 2.2 or2.3 as shown in FIG. 7A) for the display panel having positive LC. Forthe display panel having negative LC, the contrast ratio of the displaypanel is higher than 1350 when the absolute voltage difference betweenthe transparent conductive layer 230 and the common electrode 273 is ina range from 0V to 5V ; the contrast ratio of the display panel dropssignificantly when the voltage difference between the transparentconductive layer 230 and the common electrode 273 is greater than 4V orsmaller than 1V ; and the contrast ratio of the display panel dropsslightly when the absolute voltage difference between the transparentconductive layer 230 and the common electrode 273 is greater than 3V orsmaller than 2V. Therefore, the real number x may be 0, 1, 2, or anyreal number in a range from 0 to 2, and the real number y may be 2, 2.3,3, 4, or any real number in a range from 2 to 5 (e.g. 2, 2.1, 2.2, 2.3,2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 4 or 5 as shown in FIG. 7C) for thedisplay panel having negative LC. The circuit providing the voltage tothe transparent conductive layer 230 is designed according to theabsolute voltage difference between the transparent conductive layer 230and the common electrode 273, and therefore a voltage value in theaforementioned range can be chosen as the absolute voltage differencebetween the transparent conductive layer 230 and the common electrode273 according to the type of liquid crystal, the transmittance, thecontrast ratio and the design of the circuit providing the voltages.

FIG. 9A and FIG. 9B are diagrams illustrating waveforms of the voltagesof the pixel electrode 272, the common electrode 273 and the transparentconductive layer 230 in different frame periods in accordance with anembodiment. In the embodiment, frame periods N to (N+5) are shown inFIG. 9A and FIG. 9B, in which N is a positive integer. The polarity ofthe liquid crystal molecule is reversed in adjacent frame periods. To bespecific, the voltage of the pixel electrode 272 have a waveform 910which amplitude is in a range from −5V to 5V. Note that the waveform 910only represents the maximum absolute voltage of the pixel electrode 272in each frame period in FIG. 9A. However, the voltage of the pixelelectrode 272 may be in the range from 0 to 5V in the frame periods N,(N+2) and (N+4), and in the range from 0 to −5V in the frame periods(N+1), (N+3) and (N+5). The voltage of the common electrode 273 has awaveform 920 which amplitude is fixed at 0V. In the frame periods N,(N+2) and (N+4), the voltage of the pixel electrode 272 is greater thanor equal to the voltage of the common electrode 273. In the frameperiods (N+1), (N+3) and (N+5), the voltage of the pixel electrode 272is smaller than or equal to the voltage of the common electrode 273.

In the embodiment of FIG. 9A, the voltage of the transparent conductivelayer 230 has a waveform 930 which is overlapped with the waveform 920.In other words, the voltage of the transparent conductive layer 230 andthe voltage of the common electrode 273 are the same, and the voltagedifference between the transparent conductive layer 230 and the commonelectrode 273 is 0V. However, in the embodiment of FIG. 9B, the voltageof the transparent conductive layer 230 has a waveform 940, and theabsolute voltage difference between the waveform 940 and the waveform920 is X. The sign of the voltage difference between the transparentconductive layer 230 and the common electrode 273 changes due to thepolarity reversal. To be specific, in the frame period N, (N+2) and(N+4), the voltage of the transparent conductive layer 230 is greaterthan or equal to the voltage of the common electrode 273; in the frameperiods (N+1), (N+3) and (N+5), the voltage of the transparentconductive layer 230 is smaller than or equal to the voltage of thecommon electrode 273. In other words, in the embodiment of FIG. 9B, thevoltage of the common electrode 273 has a direct current (DC) waveform,but the voltage of the transparent conductive layer 230 has analternative current (AC) waveform. For example, as discussed above, ifpositive LC is adopted, the absolute voltage difference between thetransparent conductive layer 230 and the common electrode 273 ispreferably 1.7V ; and if negative LC is adopted, the absolute voltagedifference between the transparent conductive layer 230 and the commonelectrode 273 is preferably 2V. Therefore, in the frame periods N, (N+2)and (N+4), the amplitude of the waveform 940 for the display panel withpositive LC may be set as 1.7 V, and the amplitude of the waveform 940for the display panel with negative LC may be set as 2V. In the frameperiods (N+1), (N+3) and (N+5), the amplitude of the waveform 940 forthe display panel with positive LC may be set as −1.7V, and theamplitude of the waveform 940 for the display panel with negative LC maybe set as −2V (that is, X is equal to 1.7 or 2). However, the amplitudeof the waveform 940 is not limited thereto. A preferred absolute voltagedifference between the transparent conductive layer 230 and the commonelectrode 273 can be chosen according to the type of the liquid crystal(positive or negative), the contrast ratio and the transmittance so asto design the waveform 940.

In the embodiments of FIG. 9A and FIG. 9B, the voltage of the commonelectrode 273 is fixed and has DC waveform. In the embodiment of FIG.9A, the voltage of the transparent conductive layer 230 is equal to thevoltage of the common electrode 273, and thus both of the voltages ofthe transparent conductive layer 230 and the common electrode 273 haveDC waveforms. In the embodiment of FIG. 9B, the voltage of thetransparent conductive layer 230 is different from the voltage of thecommon electrode 273, and the voltage of the transparent conductivelayer 230 has to change in different frame periods because the polarityof the liquid crystal molecule is reversed in different frame periods.That is to way, the voltage of the transparent conductive layer 230 hasAC waveform.

Referring to FIG. 9C, FIG. 9C is a diagram illustrating waveforms of thevoltages of the pixel electrode 272, the common electrode 273 and thetransparent conductive layer 230 in different frame periods inaccordance with an embodiment. The voltage of the pixel electrode 272has a waveform 960, the voltage of the common electrode 273 has awaveform 970, and the voltage of the transparent conductive layer 230has a waveform 980. The difference between FIG. 9A, FIG. 9B and FIG. 9Cis that the voltage of the common electrode is fixed in FIG. 9A and FIG.9B (that is, the voltage of the common electrode is DC); but in FIG. 9C,the voltage of the common electrode changes along with time (that is,the voltage of the common electrode has AC waveform) and it is alsoreferred to as VCOM modulation. The range of the voltage of the pixelelectrode 272 is narrowed by modulating the voltage of the commonelectrode 273, and thus the cost of a source driver is reduced. As shownin FIG. 9C, the amplitude of the waveform 970 for the common electrode273 is 0V or 5V depending on which frame period it is in, and thewaveform 960 for the pixel electrode 272 is in a range from 0V to 5V.

In the frame periods N, (N+2) and (N+4), the voltage of the transparentconductive layer 230 (i.e. the waveform 980) is greater than or equal tothe voltage of the common electrode 273 (i.e. the waveform 970); in theframe periods (N+1), (N+3) and (N+5), the voltage of the transparentconductive layer 230 (i.e. the waveform 980) is smaller than or equal tothe voltage of the common electrode 273 (i.e. the waveform 970). Inother words, in the embodiment of FIG. 9C, the voltage of the commonelectrode 273 and the voltage of the transparent conductive layer 230have AC waveforms. For example, as discussed above, the absolute voltagedifference between the transparent conductive layer 230 and the commonelectrode 273 is preferably set as 1.7V if positive LC is adopted; andthe absolute voltage difference between the transparent conductive layer230 and the common electrode 273 is preferably set as 2V is negative LCis adopted. Therefore, the amplitude of the waveform 980 may be set as1.7V for the display panel with positive LC or 2V for the display panelwith negative LC in the frame periods N, (N+2) and (N+4); the amplitudeof the waveform 980 may be as 3.3V for the display panel with positiveLC or 3V for the display panel with negative LC in the frame periods(N+1), (N+3) and (N+5); and that is, X is equal to 1.7 or 2. Similarly,the amplitude of the waveform 980 is not limited thereto. A preferredabsolute voltage difference between the transparent conductive layer 230and the common electrode 273 can be chosen according to the type of theliquid crystal (positive or negative), the contrast ratio and thetransmittance so as to design the waveform 980. Note that in theembodiments of FIG. 9A and FIG. 9B, the voltage of the pixel electrode272 is in a range from −5V to 5V, and the voltage of the commonelectrode 273 is fixed at 0V. However, the invention is not limitedthereto. In other embodiments, the voltage of the common electrode 273may be set as Y volts, in which Y is a real number not equal to 0. Thevoltage of the pixel electrode 272 is in a range from (−5+Y) to (5+Y)volts; the voltage of the transparent conductive layer 230 is fixed at Yvolts (similar to the embodiment of FIG. 9A), or the absolute voltagedifference between the transparent conductive layer 230 and the commonelectrode 273 is fixed (similar to the embodiment of FIG. 9B). In otherswords, in FIG. 9A or FIG. 9B, if the waveform 920 for the voltage of thecommon electrode 273 is shifted upward or downward by Y volts, thewaveform 910 for the voltage of the pixel electrode 272 is synchronouslyshifted upward or downward by Y volts, and the waveform 930 or 940 forthe voltage of the transparent conductive layer 230 is synchronouslyshifted upward or downward by Y volts.

Similarly, in the embodiment of FIG. 9C, if the waveform 970 for thevoltage of the common electrode 273 is shifted upward or downward by Yvolts, the waveform 960 for the voltage of the pixel electrode 272 issynchronously shifted upward or downward by Y volts, and the waveform980 for the voltage of the transparent conductive layer 230 issynchronously shifted upward or downward by Y volts. For example, assumethe absolute voltage difference between the transparent conductive layer230 and the common electrode 273 is set as 1.7V, and the waveform 970(i.e. the voltage of the common electrode 273) is shifted upward by 1V.In other words, it is assumed that the voltage of the common electrode273 is 1V in the frame periods N, (N+2) and (N+4), and is 6V in theframe periods (N+1), (N+3) and (N+5). Consequently, the waveform 960(i.e. the voltage of the pixel electrode 272) is synchronously shiftedupward by 1V, and the waveform 980 (i.e. the voltage of the transparentconductive layer 230) is synchronously shifted upward by 1V. That is tosay, the maximum voltage of the pixel electrode 272 is 6V, and thevoltage of the transparent conductive layer 230 is 2.7V in the frameperiods N, (N+2) and (N+4); the minimum voltage of the pixel electrode272 is 1V, and the voltage of the transparent conductive layer 230 is4.3V in the frame periods (N+1), (N+3) and (N+5).

In addition, in the embodiments of FIG. 9A, FIG. 9B and FIG. 9C, thevoltage difference between the pixel electrode 272 and the commonelectrode 273 is in a range from −5V to 5V, but the invention is notlimited thereto. In other embodiments, the voltage difference betweenthe pixel electrode 272 and the common electrode 273 may be in a rangefrom −Z volts to Z volts, in which Z is a real number not equal to 5.

Note that although the structure of FIG. 2C is adopted in theembodiments of FIG. 7A to FIG. 8E, but the invention is not limitedthereto. The difference between FIG. 2B/FIG. 2D and FIG. 2C is avariance of the sequence of the color filter layer 241/black matrixlayer 242, the transparent conductive layer 230 and the over-coatinglayer 250 stacked on the second substrate 220. The voltage range for thetransparent conductive layer 230 and the common electrode 273 (so that apreferred contrast ratio and transmittance can be obtained) described inthe embodiments of FIG. 7A and FIG. 8E may be applied to the structuresof FIG. 2B and FIG. 2D, and the detail will not be repeated.

Moreover, the transverse-electric-field type display panel of FIG. 2C isadopted in the embodiments of FIG. 7A to FIG. 8E, that is, the pixelelectrode 272 is beneath the common electrode 273, the pixel electrode272 has a plate structure, and the common electrode 273 has the slits273 s. However, the preferred voltage ranges for the transparentconductive layer 230 and the common electrode 273 described in theembodiments of FIG. 7A to FIG. 8E may be applied to othertransverse-electric-field type display panels. For example, referring toFIG. 10A and FIG. 10B, FIG. 10A is a diagram illustrating the top viewof the display panel in accordance with another embodiment, and FIG. 10Bis a diagram illustrating a cross-sectional view of the display panelalong a cut line II-II′ in FIG. 10A. Note that the second substrate, thetransparent conductive layer, the color filter layer, the black matrixlayer and the over-coating layer are not shown in FIG. 10B. People inthe art should be able to apply the disposition of the second substrate,the transparent conductive layer, the color filter layer, the blackmatrix layer and the over-coating layer of FIG. 2B-2D to thecross-sectional structure of FIG. 10B. The difference between FIG. 10Aand FIG. 2A is that, in FIG. 10A, the pixel electrode 272 has multipleslits 272 s which are interlaced with the slits 273 s of the commonelectrode 273. Referring to FIG. 10C, the difference between FIG. 100and FIG. 2B is: in the embodiment of FIG. 2B, the pixel electrode 272 isbeneath the common electrode 273, and the common electrode 273 has theslits 273 s; in the embodiment of FIG. 10C, the pixel electrode 272 isabove the common electrode 273, the pixel electrode 272 has the slits272 s, and the common electrode 273 has a plate structure. In thestructure of FIG. 10C, the common electrode 273 is formed on theinsulation layer 291, and an insulation layer 292 is formed between thecommon electrode 273 and the pixel electrode 272. Referring to FIG. 10D,the difference between FIG. 10D and FIG. 10B is: in the embodiment ofFIG. 10B, the pixel electrode 272 is beneath the common electrode 273,and the pixel electrode 272 and the common electrode 273 respectivelyhave the slits 272 s and the slits 273 s interlaced with each other; inthe embodiment of FIG. 10D, the pixel electrode 272 is above the commonelectrode 273, and the pixel electrode 272 and the common electrode 273respectively have the slits 272 s and the slits 273 s interlaced witheach other. Referring to FIG. 10E and FIG. 10F, FIG. 10E is a diagramillustrating the top view of a pixel structure in a IPS display panel,and FIG. 10F is a diagram illustrating a cross-sectional view of thedisplay along with a cut line III-III′ in FIG. 10E. As shown in FIG. 10Eand FIG. 10F, the pixel electrode 372 and the common electrode 373 areformed on the same surface of the insulation layer 293. In other words,the pixel electrode 372 and the common electrode 373 are disposed on theinsulation layer 293 coplanarly. The material of the pixel electrode 372and the common electrode 373 may include transparent conductivematerial. The pixel electrode 372 and the common electrode 373respectively include multiple finger-type electrodes, and thefinger-type electrodes of the pixel electrode 372 are interlaced withthe finger-type electrodes of the common electrode 373. Similarly, thesecond substrate, the transparent conductive layer, the color filterlayer, the black matrix layer and the over-coating layer are not shownin FIG. 10C, FIG. 10D and FIG. 10F. People in the art should be able toapply the disposition of the second substrate, the transparentconductive layer, the color filter layer, the black matrix layer and theover-coating layer of FIG. 2B-2D to the cross-sectional structures ofFIG. 10C, FIG. 10D and FIG. 10F. The preferred voltage range for thetransparent conductive layer 230 and the common electrode 273 describedin the embodiments of FIG. 7A to FIG. 8E may be applied to thetransverse-electric-field type display panel shown in FIG. 10A to FIG.10F. In the display panel provided in the embodiments of the invention,the transparent conductive layer is disposed between the secondsubstrate and the liquid crystal layer to reduce the cost of the displaypanel and also to provide the shielding function from interference ofelectromagnetic wave and the accumulation of electrostatic charges. Inaddition, the display panel has better contrast ratio and transmittanceby controlling the voltage of the transparent conductive layer within ina particular range.

Although the present invention has been described in considerable detailwith reference to certain embodiments thereof, other embodiments arepossible. Therefore, the spirit and scope of the appended claims shouldnot be limited to the description of the embodiments contained herein.It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure of the presentinvention without departing from the scope or spirit of the invention.In view of the foregoing, it is intended that the present inventioncover modifications and variations of this invention provided they fallwithin the scope of the following claims.

What is claimed is:
 1. A display panel, comprising: a first substrate; asecond substrate disposed opposite to the first substrate; a pluralityof pixel structures disposed between the first substrate and the secondsubstrate, wherein each of the pixel structures comprises a thin filmtransistor, a pixel electrode and a common electrode; a liquid crystallayer disposed between the pixel structures and the second substrate;and a transparent conductive layer disposed between the second substrateand the liquid crystal layer, wherein when a liquid crystal molecule ofthe liquid crystal layer is a positive liquid crystal molecule, anabsolute voltage difference between the transparent conductive layer andthe common electrode is smaller than or equal to 2.3 volts(V); or whenthe liquid crystal molecule of the liquid crystal layer is a negativeliquid crystal molecule, the absolute voltage difference between thetransparent conductive layer and the common electrode is smaller than orequal to 5V.
 2. The display panel of claim 1, wherein when the liquidcrystal molecule of the liquid crystal layer is the positive liquidcrystal molecule, the absolute voltage difference between thetransparent conductive layer and the common electrode is smaller than orequal to 2.3V and is greater than or equal to 1V.
 3. The display panelof claim 2, wherein when the liquid crystal molecule of the liquidcrystal layer is the positive liquid crystal molecule, the absolutevoltage difference between the transparent conductive layer and thecommon electrode is smaller than or equal to 2V and is greater than orequal to 1.4V.
 4. The display panel of claim 3, wherein when the liquidcrystal molecule of the liquid crystal layer is the positive liquidcrystal molecule, the absolute voltage difference between thetransparent conductive layer and the common electrode is equal to 1.7V.5. The display panel of claim 1, wherein when the liquid crystalmolecule of the liquid crystal layer is the negative liquid crystalmolecule, the absolute voltage difference between the transparentconductive layer and the common electrode is smaller than or equal to 4Vand is greater than or equal to 1V.
 6. The display panel of claim 5,wherein when the liquid crystal molecule of the liquid crystal layer isthe negative liquid crystal molecule, the absolute voltage differencebetween the transparent conductive layer and the common electrode issmaller than or equal to 3V and is greater than or equal to 2V.
 7. Thedisplay panel of claim 6, wherein when the liquid crystal molecule ofthe liquid crystal layer is the negative liquid crystal molecule, theabsolute voltage difference between the transparent conductive layer andthe common electrode is equal to 2V.
 8. The display panel of claim 1,further comprising: an insulation layer disposed on the thin filmtransistor, wherein the insulation layer is disposed on the pixelelectrode, the common electrode is disposed on the insulation layer, andthe common electrode has a plurality of slits.
 9. The display panel ofclaim 1, further comprising: an insulation layer disposed on the thinfilm transistor, wherein the insulation layer is disposed on the commonelectrode, the pixel electrode is disposed on the insulation layer, andthe pixel electrode has a plurality of slits.
 10. The display panel ofclaim 1, further comprising: an insulation layer disposed on the thinfilm transistor, wherein the pixel electrode and the common electrodeare disposed on the insulation layer coplanarly, each of the commonelectrode and the pixel electrode respectively comprises a plurality offinger-type electrodes, and the finger-type electrodes of the commonelectrode are interlaced with the finger-type electrodes of the pixelelectrode.
 11. The display panel of claim 1, further comprising: a blackmatrix layer disposed between the second substrate and the liquidcrystal layer, wherein the transparent conductive layer is disposedbetween the second substrate and the black matrix layer.
 12. The displaypanel of claim 1, further comprising: a black matrix layer disposedbetween the second substrate and the liquid crystal layer; and aover-coating layer disposed between the black matrix layer and theliquid crystal layer, wherein the transparent conductive layer isdisposed between the black matrix layer and the over-coating layer. 13.The display panel of claim 1, further comprising: a black matrix layerdisposed between the second substrate and the liquid crystal layer; anda over-coating layer disposed between the black matrix layer and theliquid crystal layer, wherein the transparent conductive layer isdisposed between the over-coating layer and the liquid crystal layer.14. The display panel of claim 1, wherein a voltage of the transparentconductive layer is equal to a voltage of the common electrode in afirst frame period and a second frame period next to the first frameperiod, and the voltage of the common electrode in the first frameperiod is the same as that in the second frame.
 15. The display panel ofclaim 1, wherein a voltage of the transparent conductive layer isgreater than a voltage of the common electrode in a first frame period,the voltage of the transparent conductive layer is smaller than thevoltage of the common electrode in a second frame period next to thefirst frame period, and the voltage of the common electrode in the firstframe period is the same as that in the second frame.
 16. The displaypanel of claim 15, wherein the absolute voltage difference between thetransparent conductive layer and the common electrode in the first frameperiod is the same as that in the second frame period.
 17. The displaypanel of claim 15, wherein the voltage of the common electrode has adirect current (DC) waveform, and the voltage of the transparentconductive layer has an alternative current (AC) waveform.
 18. Thedisplay panel of claim 1, wherein a voltage of the transparentconductive layer is greater than or equal to a voltage of the commonelectrode in a first frame period, the voltage of the transparentconductive layer is smaller than or equal to the voltage of the commonelectrode in a second frame period next to the first frame period, andthe voltage of the common electrode in the first frame period is smallerthan that in the second frame.
 19. The display panel of claim 18,wherein the absolute voltage difference between the transparentconductive layer and the common electrode in the first frame period isthe same as that in the second frame period.
 20. The display panel ofclaim 18, wherein the voltage of the common electrode and the voltage ofthe transparent conductive layer have an alternative current (AC)waveform.